Priorities...


Which would you prioritise for an upgrade - mono blocks, pre amp or speakers? 
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I mean these questions in a friendly way: Why ask for detailed system advice without listing a complete system?  And what are your long-term goals for the system? What kind of musical experience are you after?

I don't mean to single you out, by the way. Lots of people ask for system advice without giving full context.  Photos would help too, so as to determine whether advice is appropriate for a particular space.
Again, what are your sonic goals beyond what you have now, what are your sources and ancillaries? Without knowing what these are, as much as we'd like to, it is difficult to make educated/experienced recommendations.
As an owner of Tannoys, you do not need Gamut monoblocks to power them.  Yes, you need some clean power, but quality is the most important factor.  Decide if you want tube or ss.  As for me, I went tube pre and ss amp for my DC8s.  From my research, the 10As are perhaps the "brightest" of the upper end Tannoys. No, I've not heard them to confirm.  A nice tube amp with at least 50 wpc or a ss amp with 100 wpc will be just the ticket.  If it were me, I'd sell the Gamuts, buy a good Integrated amp and get into the Prestige line....Turnberrys i.e.  Good luck and let us know your thoughts so maybe we can be of further help.  Regards.....
Buy nothing until you know it will improve...bring delight to your music.   I would listen to your current system .....go to concerts, enjoy life.
Thank you all for the input.

I will mention again that there is nothing wrong with the sound of my current system; it's very enjoyable. The situation is primarily capitalising on the opportunity of a very good deal but requires a possible compromise. 
I say possible as I may be able to replace the GamuTs with a similar performing alternative. But it raises the question is the DC10A a quantum leap over the DC10T...??
This is where DC10A owners contribute with their opinions of their performance...

@carmenc - are you suggesting the M250i monos are not quality amps...?!